Is not spring the time to have some fun? That was quite a long moment ago someone invited to guess a lens. Meanwhile members' experience is growing, as well as common knowledge about how lenses behave themselves. I recently got an impressively good quality lens and very curious to see if it is possible to catch its parameters from the shots.

So, it is obviously a MF. It was produced in the 1970-80. Some of you certainly have it. I presume, Pierre, Steve, sergtum, Klaus are among its owners. As long as you guys have hundreds of lenses, I do not risk too much saying that.

Basing on the image sharpness, bokeh, in-focus and OOF separation, could you share your ideas about:

1. Which focal range and maximum aperture it has.
2. Which optical design.
3. Finally, what lens it is.

Some shots follow.

#1 The lens is really sharp, it has a very good resolving power.

#2 That is also visible in 100% crops.

#3 The lens' natural contrast is a bit low but when you boost it without exagerration, the picture gets really punchy.

#4 With an APS-C camera and slightly closed aperture even the image borders are stunningly detailed and sharp, as this unprocessed 100% crop shows.

#5 Under some circumstances stray light may create an effect you see on the right side of the shot. But it is honestly a very rare occasion.

#6 This is how it behaves when it gets darker.

#7 And here is how the lens genuinely dissolves from in-focus to OOF.

Any ideas?

Last edited by alex ph on Sun Apr 23, 2017 1:40 pm; edited 1 time in total

Sergtum, jamaeolus, nice guesses! I looked at both Orestor and Ultron shots in the net. They share indeed much similar in main subject sharpness and OOF rendering. Still, the one of the quiz is none of them.

The sort of wide-eye shaped out of focus highlights in #7 give me a hint, at least, that this is a fast lens. Possibly even in the neighborhood of f/1.2. I see these same sorts of highlights with my fast Canon glass. I'm not an optical expert at all, so I can't even make an educated guess. About all I can make is a wild-ass guess. So I'll go with what I know.

Cooltouch That was what I did as well, just based on instinct and recalling images I have take with my ultron. I am betting against the !.2 as depth of field seems to wide but I have been wrong (many times!) before._________________photos are moments frozen in time

Luisalegria, it is a Double Gauss! Not of 7, but of 6 elements. All of you who gave a guess referring to 50mm lenses were close or right about the optical design. Your instincts were correct! But other parameters are different. I mean, it is a non-50mm Double Gauss. Cooltouch, this lens is not as fast as that, even if it separates very well in- and out-of-focus.

Shorter than 50mm fast Double Gauss -
Well assuming its a standard 35mm camera lens and not some exotic piece of macro kit or a weird projection lens (which are all possible of course) there aren't a lot of options.

There are a lot of Japanese 45mm-range Double Gauss f/1.4-f/2 lenses that can be scavenged from old rangefinders - The Yashica Lynx 45/1.4 perhaps. Some people have mounted them for NEX and such.

That is a cheap way, if you are handy with tools to get the mount attached.

Then you could be going with the expensive stuff, a Leica Summilux 35/1.4 or Canon 35/1.5 or a Voigtlander._________________I like Pentax DSLR's, Exaktas, M42 bodies of all kinds, strange and cheap Japanese lenses, and am dabbling in medium format/Speed Graphic work.

I had the first thought about the projection lens. I drove it away. After the image of the optical scheme, I'm almost certain that the objective lens is a projection lens f92 (from the projector ЛЭТИ).

Sergtum, you are too strong! Yes, that is a Soviet projection lens F-92, with fixed aperture f2. As images come overexposed at a bright sun or even in a good daylight, I made two circles of black paper that I put in front of the lens. I presume, one gives around f2.8-3.5 and the other around f4.5-5.6 of aperture value.

I do not put here a shot of the lens itself. Pierre previously did all the work. I have an identical copy.

I am very impressed with the IQ the lens renders, "airy" feeling and great separation of image plans. Especially when light conditions are not too contrasty, the lens easily shows all these qualities and overcomes in resolution most of what I tried before. Please, have a look at this handheld shot, contrast slightly boosted:

From where I take this 100% crop:

The lens is pretty heavy on NEX. But aside a stunningly good image quality it gives you a real taste for 135mm that you have with an APS-C camera. Knowing that you may find it for 30-40 euros (shipping excluded) and then your shots might be easily taken for Ultron or Nocton made, it is a real discovery.